Weighing device

ABSTRACT

A weighing device comprising a frame extending between and supported by a pair of rails for movement therewith, a load supporting platform adapted to engage the wheels of a railway guided vehicle and a plurality of load sensing means supporting the platform on the frame.

United States Patent I191 Ahl et al. 1 Feb. 6, 1973 [5 WElGHlNG DEVICE 3,092,195 6/1963 Von Petery ..177/163 Inventors: Nils Goran Lars Herbert FOREIGN PATENTS OR APPLICATIONS Larsson, both of Vasteras, Sweden 121,552 9/1967 Czechoslovakla ..l77/163 947,761 7/1949 France [737] tiu ffitf'ii 1YF? ?a YYFf5 958,141 3/1950 France mums [22] Filed: Sept. 16, 1971 Primary Examiner-George H. Miller, Jr. [21] Appl' L047 Attorney-Yount & Tarolli [30] Foreign Application Priority Data I [57] ABSTRACT Sept. 21, I970 Sweden ..12802/70 A weighing device a K mending between and supported by a pan of F8118 for movement therewith, a load supporting platform adapted to [52] US. Cl ..l77/136, 177/163 engage the wheels of a railway guided vehicle and a [51] Int. Cl. ..G0lg 19/08 plurality f l d sensing means supporting the plat- [58] Field of Search ..l77/l26, 136, 163,211 form on the frama 5 References Cited 21 Claims, 18 Drawing Figures UNITED STATES PATENTS Aihara ..l77/l63 E I- lb WEIGHING DEVICE This invention relates to weighing devices and, more particularly, to a device for weighing railway guided vehicles.

It is well known that weighing of railway guided vehicles can be accomplished by means of stationary platform scales which are arranged in weighing pits in the path of the vehicle. One example of such a scale is disclosed in a pamphlet published by Toledo Scale Corporation, Toledo, 'Ohio, and entitled Toledo Steel Master Levers." Typically, there is provided on the upper surface of the platform, a rail of some kind as, for

' example, a channel beam for a vehicle having rubber wheels or a rail in the case of railway cars. In either instance, the upper surface of the rail carried by the platform is in the same plane as the fixed ground supported rails adjacent to the scale but the platform rails are disconnected from the fixed rails by an open joint at either end so that the rail section carried by the platform scale is free to move vertically. In such arrangements, the load resting on the scale may be sensed by various means such as, for example, a mechanical weighing system or by the use of load cells.

Such systems have several drawbacks. For example, the usual requirement of a stiff solid support for the scale has been embodied in the prior art systems through the use of massive, expensive scale foundations. Obviously, such foundations require a permanent or stationary installation thereby precluding any possibility of transporting the scale from one weighing site to another. Another problem in using such prior art weighing systems in weighing railway cars is that the scales cannot be installed at locations where trains may be passing at full speed. The reason for this is the substantial wear which would occur at the joint between the weigh platform and the adjoining rails as well as the damaging stresses which would be imposed on the weighing system by the rapidly moving cars.

Various attempts have been made to devise weighing systems which will overcome these, as well as other, problems. However, almost invariably, these systems use some form of a stationary scale which is associated with a section of the rail and which is designed to sense the load imposed on the upper surface of the rail. Examples of typical prior art systems may be in Pat. U.S. Pat. Nos. 3,004,152, 3,085,642 and 3,159,227; British Pat. Nos. 820,969, 797,161 and 832,389; German Pat. No. DEF/1,079,338; French Pat. Nos. 1,292,587 and 974,974 and Swedish Pat. No. 217,810.

ltis the principal object of this invention to provide a weighing system for railway guided vehicles which overcomes the foregoing problems encountered with the prior art systems and which is capable of achieving acceptable weighing accuracy.

It is a further object of this invention to provide a weighing system for railway guided vehicles which eliminates the need for massive foundation supports and which thereby enables the weighing system to be installed at any desired location.

Still another object of this invention is to provide a Still a further object of this invention is to provide a weigh device for railway vehicles which may readily be moved from one weighing site to another weighing site.

These objects, as well as others, are achieved in the present invention by departing from the basic principles on which prior art systems have been based and using to advantage an approach which is essentially opposite to that used in prior art systems. More particularly, and as noted previously, conventional prior art weighing systems utilize a massive foundation or some other form of rigid support to avoid any unwanted deflection in the weighing system. This invention proposes to eliminate such foundation supports and provide a weighing device which is, in its preferred form, supported directly on the rails and which is free to follow the movement of the rails as a railway car passes thereover. More specifically, the invention provides a weighing device which comprises a frame that extends between and is supported on a pair of rails, a

load platform having a vehicle engaging'surface thereon positioned adjacent to the rail with a plurality of load sensing transducer means such as load cells or the like supporting the load receiving platform on the frame in a position to be engaged by the rail guided vehicle. In this manner, any deflection'of either rail as the car passes thereover is followed by the weighing device so that a perfectly defined force is applied to the load sensing means irrespective of deflections which may occur either in the rail or the ties supporting the rail.

A weighing device, according to this invention, provides a number of advantages over conventional railway weighing systems. As noted previously, the need for expensive foundation supports is eliminated. As a result, the invention can be incorporated in an existing rail system without the need for any modification of that system. Moreover, the weighing device can be easily moved from location to location as required. Still further, in the event of a malfunction in the weighing system, the weighing device is relatively easily removed so that normal rail traffic can continuewithout interruption across the weighing station.

The weighing device of the instant invention is particularly suitable for use with automatic loading or unloading stations for different types of bulk material such as coal, ore, scrap, lumber, grain or the like, in

tial assistance in complying with safety regulations governing railway cars and the risk of a derailment because of incorrect load distribution is greatly reduced.

Other objects, features and advantages of the invention will be more apparent upon a complete reading of the following discription which, together with the attached drawings, discloses but a few of the forms which the invention may take.

Referring now to the drawings wherein like reference numbers indicate like parts in the various views:

FIG. 1a is a crosssectional view through a weighing device constructed according to the invention and installed in an existing rail system.

FIG. Ibis a sectional view along line A-A of FIG. la.

FIG. 2 is a sectional view, similar to FIG. 1, but showing a modified form of a weighing device.

FIG. 3 is a sectional view illustrating a further modified form of a weighing device.

FIG. 4a is a sectional view along line AA of FIG 4b and illustrates a further modified form of a weighing device according to this invention.

FIG. 4b is a plan view of a modified form of weighing device.

FIG. 40 is a fragmentary sectional view of the device of FIG. 4a, and illustrating the weighing device in an inoperative position.

FIG. Sa is a longitudinal sectional view along line B B of FIG. 4b.

FIG. 5b is a sectional view along line CC of FIG. 4b.

FIGS. 6 and 7 illustrate two different modified forms of weigh device for weighing vehicles with widened vehicle wheels.

FIGS. 8 and 9 show two alternative forms of weigh devices constructed in accordance with this invention and which are supported for movement along the rails.

FIGS.- 10a, 10b and 100 illustrate a further modified form of the weigh device.

FIGS. 11 and 12 illustrate two alternative forms for weighing of the vehicle through engagement of rollers or cams on either the vehicle or the weighing device.

Referring now more in detail to the drawings, there is illustrated in FIG. la a weighing device constructed in accordance with the principle of this invention and incorporated in an existing rail system. As illustrated, a vehicle having a pair of flanged wheels W is adapted to be supported on and travel along a pair of conventional rails. The weigh device includes a loading platform 3 having removable and replaceable wheel engaging wear surfaces 2 adapted to engage and support the flanged portions 1 of the vehicle wheel W. The loading platform 3 rests on the load application point of a plurality of conventional load cells 4. The load cells 4 are supported on a frame 5 which preferably comprises a pair of parallel beams extending transversely of the rails with either end thereof being supported by surfaces on support rails 9 each of which engage the web of the rail and which rest against the upper surface of the foot or base 10 of the rail. The transverse extend of frame 5 is such that it maintains the support rails 9 in the position shown in FIG. la. In this manner, the frame 5 is supported solely by the rails and, as a result, will follow any movement or deflection of the rails as the vehicle passes thereover.

As is apparent from FIG. lb, the wheel engaging surface 2 on the platform 3 is provided with tapered or inclined ends-6 which rise toward a middle section 7 so that as a vehicle passes over the weigh device, the wheel will roll up the tapered portion 6 on to the middle section 7 and thereby be entirely separated form the wheel engaging surface of the rail. Appropriate tie rods 8 which are stiff or rigid in the horizontal direction but readily deflectable in the vertical direction may be employed to minimize any undersirable side loading on the load cells 4.

AS shown in FIG. lb, the support rails 9 may be attached to the rails to prevent longitudinal movement of rails 9 by means of suitable clamps indicated at 11 which are clamped to the inner part of the base or foot 10 of the rails. Of course, the support rails 9 may be secured against longitudinal movement by other ap propriate means. For example, where a limited number of weighing positions are to be used, stops may be welded to the rails.

From the foregoing, it will be appreciated that the described weighing device is supported solely on the rigid foot or base of the rails. This rigid support enables the weighing device to provide weight readings of the desired degree of accuracy without the need for expensive foundation supports. It is important to.note that, because the weighing device is supported solely by the rails, any movement by the rails is followed by the weighing device. This relationship results in several important advantages. For example, the relationship between the wheel engaging surface 2 on the loading platform 3 and the vehicle wheels remains essentially constant at all times. As a result, the load forces applied to load cells 4 by the vehicle are at all times distributed among the various load cells. If one rail should deflect while the other rail does not, the manner in which the frame 5 merely rests on the two rails enables the associated end of frame 5 to follow the movement of the deflective rail and thereby maintain the proper relationship between the vehicle and the weigh device.

Another advantage of supporting the weigh device on the rail relates to the properties exhibited by a rail under load. Because the rail, and its supporting ties, flex and deflect under the wheel load, the vehicle normally moves on a somewhat lower level than the nominal level defined by the wheel engaging surface of the unloaded rail. At the same time, oscillations in the vertical plane are produced due to the deflection of the rail between adjacent supporting ties. When the train passes over a weighing device which utilizes a large massive rigid foundation, the elastic properties of the relatively rigidly supported platform rails are substantially different from the elastic properties of the ground supported rails. The vehicle thus experiences a sudden stiffening of the rail support which substantially reduces the flexing of the rails and entirely eliminates the oscillations due to the deflection between rails with the result that the vehicle is lifted up". This, in turn, causes uncontrolled changes in the vertical forces acting on the vehicle as it is being weighed. However, by supporting the weigh device on the rails so that the weigh device acts as an integral part of the rail system, the wheels of the vehicle as they pass on to the loading platform experience no change in the elastic properties and the lifting up" effect is entirely eliminated.

A further advantage of supporting the weigh device directly'on the rails for movement therewith, is that only a very slight rise in elevation as the wheels pass on to the loading platform is required to separate the wheels from the rails. Any movement of the rails will be followed by a corresponding movement of the weigh device which will maintain the separation between the wheels and the rails while weighing is being accomplished.

A further advantage of the described weighing device is its ease of installation and ready transportability. As an example of this advantage, consider an automatic loading station at a modern ore depot which uses a tunnel through which the railway cars to be loaded pass with loading openings arranged in the celling or roof of the tunnel. At such a station, the ore is dumped into the cars as the train passes beneath the loading openings. Normally, there are a large number of loading openings which are used alternatively and selectively. To obtain the maximum utilization of the train, each car must be weighed and the loading controlled so that all cars are fully and equally loaded. With conventional weighing technology, it has been necessary to build a scale foundation and a scale for each individual loading position. Obviously, this requires a very large investment. Moreover, in the event any one weighing location should require service, the entire rail system was disrupted. However, with a weighing device as described, not only is the cost of the system drastically reduced but it is possible to replace any one unit in a very short period of time so that disruption of the loading operation is minimized.

A further illustration of the advantages of this invention is with reference to loading and unloading of bulk material from ships. Since ships areof different lengths, have different distances between hatches and may be positioned at a pier at various locations, the described weigh device provides a scale which may be quickly positioned at any desired location on the tracks adjacent the pier where loading and unloading are to be accomplished.

Referring now to FIG. 2, a modified form of the weigh device and its support is illustrated. As shown, the load cells 4 of FIG. la, have been replaced by load sensing devices in the form of shear sensing transducers 4' which, as is well known, operate on the principle of a bending stressed beam. In addition, the support rails 9 have been eliminated and the frame 5 is designed to rest on the foot of the rail closely adjacent to the rail centerline. In this manner, the vehicle load is evently distributed on the rail support and concentration of stresses in the rail foot are minimized. In addition, the frame 5' is restrained against any lateral movement by engagement with the web of the rail.

A further alternative support of the weigh device is illustrated in FIG. 3 wherein the device is shown as resting directly on ties 16 with the frame 5" being restrained against lateral movement by abutting engagement with the rail foot 10. This latter arrangement is not preferred since the well-defined support for the weigh device obtained with the arrangements shown in FIG. 1a and FIG. 2 may not be obtained with the FIG. 3 embodiment due to possible differences in movement between the rail and the ties. However, this problem is eliminated if the tie is so supported and constructed that the tie and rail move as a unit. I

Referring now to the embodiment illustrated in FIGS. 4a-c and 5a and 5b, a weighing device is provided which is hingedly jointed in several planes to assure capability of the weighing device to move with the movements of the rails without setting up stresses in the device or the transducers 24 associated with that device. Thus, the frame comprises a pair of crossbeams 25 which extend transversely of the rails and which are provided with support lugs 14 received in appropriaterecesses 15 (FIG. 5b) on support rails 29. The load supporting platform comprises a pair of parallel beams 30 which extend longitudinally of the rails and on which are formed the loading surfaces 2. The beams 30 are pivotally interconnected at approximately their mid-points by a horizontally extending axle 12. The axle 12 carries at either end thereof, eccentric pins 13 which are received in corresponding journals formed in the beams 30. A suitable actuator such as the manually operable handle 23 is connected to the axle 12 for rotating the axle to raise and lower the load receiving platform. Thus, as shown in FIG. 4a, the axle 12 is rotated to a position where the platform is in a position to engage the wheels of the vehicle while in FIG. 40 the axle has been rotated 180 to lower the platform beneath the level of the rail and allow the vehicle to pass without engaging the weigh device. While a manually operable handle 23 has been illustrated, it will be appreciated that other means such as a remote controlled motor or other suitable device could be used to rotate the axle 12. Moreover, the axle 12 may be replaced by a torsionally weak member fixedly connected to beams 30.

FIG. 6 illustrates a modified form of the weigh device in which the vehicle wheels have been made wider than the rail so that the portion of the wheel extending outwardly of the rails can cooperate with a load platform which is illustrated as being outside of the rails. Alternatively, as shown in FIG. 7, the wheels of the vehicle are illustrated as having a portion on the interior surfaces thereof which is adapted to cooperate with the weighing device.

FIGS. 8 and 9 illustrate further modified forms of the weighing device in which the device is designed to be movable along the rails for selective positioning of the weigh device. Thus, in FIG. 8 the weigh device is provided with wheels 17 which are pivotally supported on the frame 35 and which may be pivoted to a position where the wheels support the weigh device on the upper surface of the rails. Alternatively, there is illustrated in FIG. 9 pivotedly supported wheels 18 which, instead of rolling on top of the rail, are adapted to the foot of the rail and support the weigh device for movement along the rail. The device of FIG. 9 has the advantage that the weigh device can be moved under a train standing on the rail. It will, of course, be understood that the frame 35 is supported on the rails in the manner previously described when the device is in he desired location.

FIGS. l0a-c illustrate a further modification of the weigh device which is so designed that during the weighing operation the vehicle is supported by the normal rail engaging portion of the wheel periphery and not on the flange I of the wheel. A cut-out or recess 20 is formed in the rail at the weigh location so that the width of the rail at the weighing station is reduced. In addition, a recess 19 is formed in he wheel engaging upper surface of the rail. In this manner, the load receiving surface on the platform 33 is moved closer to the centerline of the rail and is so positioned that it engages the wheel as shown in FIG. 10b. An additional advantage of this arrangement is that the load receiving surface on the platform 33 is co-extensive with the main rail thereby eliminating the need for the wheels to move upward on to a loading surface. Moreover,

weighing with the embodiment of FIG. 10 can be effected entirely independently of the rear car wheels since there is no change in the elevation of the front wheels as compared to the rear wheels. However, this embodiment has the disadvantage of not being as readily transportable as other embodiments.

Referring to FIGS. 11 and 12, still further modifications of the weighing device utilizing the principles of this invention are schematically illustrated. In FIG. 11 the vehicle is provided with a wheel or roller 21 which is positioned on the vehicle such that it is adapted to engage a cam surface 22 on the loading platform 3. In FIG. 12 the parts have been reversed with the wheel or roller 24 carried on the loading platform of the weigh device and adapted to cooperate with a cam surface 23 on the vehicle.

The effects of the coupling forces between the cars on the weighing operation can be minimized by elevating one or more of the cars both before and after the car being weighed. This approach, of course, need not be used with the embodiment of FIG. 10.

While the foregoing embodiments are primarily adapted for stationary weighing, the same weighing devices can be used for in-motion weighing of cars, if desired.

From the foregoing, it will be appreciated that the described weigh device achieves the objects set forth above. Thus, the device is easily installed or removed and readily transported to any desired location. Moreover, and most importantly, the use of a frame comprising a pair of beams extending between and rigidly supported on the rails permits the weigh device to achieve weighing accuracy comparable to stationary installations without the drawbacks of such installations.

Although the invention has been described with reference to certain specific embodiments, either the illustrated embodiments nor the terminology employed in describing them is intended to be limiting; rather, it is intended to be limited only by the scope of the appended claims. 9

Having thus described the invention, what is claimed 1. A system for weighing railway guided vehicles and including;

spaced apart rail means adapted to cooperate with and support the wheels of a railway vehicle, a pair of rigid frame means extending transversely of said rail means,

said frame means including supporting means at either transverse end thereof supporting said frame means solely on said rail means at points spaced from the vehicle engaging surfaces of said rail means,

said supporting means cooperating with said rail means to permit each of said frame means to move with its associated rail means, and

load sensing means supported on said frame means adjacent to said rail means,

said load sensing means including vehicle supporting means extending longitudinally of said rail means and engagable with the vehicle to support said.

2. The system of claim 1 wherein said vehicle supporting means include roller means for engaging a cam surface on the vehicle.

3. The system of claim 1 wherein said frame means includes roller means supported thereon,

said roller means being selectively engageable with said rail means for supporting said frame means for rolling movement along said rail means.

4. The system of claim 1 wherein said supporting means comprises support rails on the interior of said rail means,

said support rails having portions thereof resting on the foot of said rail means for rigid support thereof,

said support rails further including support surfaces thereon,

said frame means being supported on said support surfaces with said frame means cooperating with said support rails to maintain said support rails against the interior of said rail means.

5. The system of claim 1 wherein said supporting means comprises end portions on said frame means resting on the foot of said rail means and engaging said rail means to restrain transverse movement of said frame means.

6. The system of claim 1 and further including means cooperating with said frame means for selectively shifting said vehicle engaging means between a vehicle supporting position and an inoperative position.

7. The system of claim 1 wherein said vehicle supporting means comprises a pair of beams extending generally parallel to said rail means, and

connecting means extending between said pair of beams, I

said connecting means being operative to permit relative vertical movement of said beams.

8. The system of claim 1 wherein said load sensing means are shear sensing bending beam type load cells.

9. The system of claim 1 wherein said vehicle supporting means engagable with the vehicle comprises a pair of wheel engaging platforms with one of said platforms being adjacent one of said rail means and the other of said platforms being adjacent the other of said rail means,

said means for delivering a signal comprising a plurality of load sensing devices with a pair of load sensing devices supporting one of said platforms on said frame means and another pair of load sensing devices supporting the other of said platform means on said frame means.

10. The system of claim 9 wherein said load sensing devices are shear sensing bending beam type load cells with each of said load cells being supported at one end thereof on said frame means; the other end of each of said load cells being operatively connected to one of said platforms.

11. The system of claim I wherein said vehicle engaging means comprises a loading platform with portions of said loading platform being positioned to be engaged by the wheels of the vehicle.

12. The system of claim 11 wherein said rail means include a recess in the vehicle engaging surface with said portions of said loading platform being positioned in said recess.

13. The system of claim 11 wherein said portions of said loading platform extend above the vehicle engaging surface of said rail means.

14. The system of claim 4 wherein said portions of said loading platform are positioned outside of said rail means.

15. A weighing device for weighing of railway guided vehicles comprising;

frame means adapted to extend between the rails and including means for supporting said frame means solely on the rails at points spaced from the vehicle engaging surfaces of the rails,

load receiving platform means comprising a pair of longitudinally extending spaced apart beams adapted to engage and support the vehicle to be weighed,

connecting means extending between said beams with said connecting means being operative to permit relative vertical movement of the ends of each beam, and

a plurality of load sensing means supported on said frame means and operative to produce a signal indicative of the magnitude of an applied load,

said load sensing means cooperating with said platform means to support said platform means on said frame means.

16. The weighing device of claim wherein said means for supporting said frame means comprises a pair of support rails each having a surface adapted to rest on the foot of said rails.

17. The weighing device of claim 15 wherein said means for supporting said frame means comprises end portions on said frame means having a configuration adapted to engage and rest on the foot of the rails.

18. The weighing device of claim 15 and further including means for selectively shifting said platform means between an operative vehicle engaging position and an inoperative position.

19. The weighing device of claim 15 and further including roller means supported on said frame means,

said roller means being adapted to engage the rails and support said device for rolling movement along the rails.

20. The weighing device of claim 15 wherein said frame means comprises a pair of spaced apart beams and said load receiving platform means comprises a pair of wheel engaging platforms with one of said wheel engaging platforms being adjacent one of the rails and the other of said wheel engaging platforms being adjacent the other of the rails,

said load sensing means comprising a plurality of signal generating devices with a pair of signal generating devices carried by one of said frame beams and another pair of signal generating devices being carried by the other of said frame beams,

each of said wheel engaging platforms being supported by signal generating devices on each of said frame beams, whereby each of said frame beams is free to follow the movement of the rail on which it is supported and said wheel engaging platforms can flexibly adapt themselves relative to position and height changes of either of said frame beams,

21. A device for weighing vehicles which are adapted to travel along rail means comprising a pair of rails and supports for the rails, said device comprising;

a first pair of spaced'apart beams adapted to extend transversely between the rails and be supported by said rail means a second pair of spaced apart beams transverse to said first pair with each beam of said second pair being adapted to be positioned adjacent to one of the rails,

load sensing means operatively supporting each end of each of said second pair of beams on said first pair of beams, and

means torsionally interconnecting said second pair of beams whereby each of said secondpair of beams can flexibly adapt themselves relative to position and height changes of said first pair of beams. 

1. A system for weighing railway guided vehicles and including; spaced apart rail means adapted to cooperate with and support the wheels of a railway vehicle, a pair of rigid frame means extending transversely of said rail means, said frame means including supporting means at either transverse end thereof supporting said frame means solely on said rail means at points spaced from the vehicle engaging surfaces of said rail means, said supporting means cooperating wIth said rail means to permit each of said frame means to move with its associated rail means, and load sensing means supported on said frame means adjacent to said rail means, said load sensing means including vehicle supporting means extending longitudinally of said rail means and engagable with the vehicle to support said vehicle and signal generating means for delivering a signal indicative of the load of said vehicle, said signal generating means supporting said vehicle supporting means on said frame means.
 1. A system for weighing railway guided vehicles and including; spaced apart rail means adapted to cooperate with and support the wheels of a railway vehicle, a pair of rigid frame means extending transversely of said rail means, said frame means including supporting means at either transverse end thereof supporting said frame means solely on said rail means at points spaced from the vehicle engaging surfaces of said rail means, said supporting means cooperating wIth said rail means to permit each of said frame means to move with its associated rail means, and load sensing means supported on said frame means adjacent to said rail means, said load sensing means including vehicle supporting means extending longitudinally of said rail means and engagable with the vehicle to support said vehicle and signal generating means for delivering a signal indicative of the load of said vehicle, said signal generating means supporting said vehicle supporting means on said frame means.
 2. The system of claim 1 wherein said vehicle supporting means include roller means for engaging a cam surface on the vehicle.
 3. The system of claim 1 wherein said frame means includes roller means supported thereon, said roller means being selectively engageable with said rail means for supporting said frame means for rolling movement along said rail means.
 4. The system of claim 1 wherein said supporting means comprises support rails on the interior of said rail means, said support rails having portions thereof resting on the foot of said rail means for rigid support thereof, said support rails further including support surfaces thereon, said frame means being supported on said support surfaces with said frame means cooperating with said support rails to maintain said support rails against the interior of said rail means.
 5. The system of claim 1 wherein said supporting means comprises end portions on said frame means resting on the foot of said rail means and engaging said rail means to restrain transverse movement of said frame means.
 6. The system of claim 1 and further including means cooperating with said frame means for selectively shifting said vehicle engaging means between a vehicle supporting position and an inoperative position.
 7. The system of claim 1 wherein said vehicle supporting means comprises a pair of beams extending generally parallel to said rail means, and connecting means extending between said pair of beams, said connecting means being operative to permit relative vertical movement of said beams.
 8. The system of claim 1 wherein said load sensing means are shear sensing bending beam type load cells.
 9. The system of claim 1 wherein said vehicle supporting means engagable with the vehicle comprises a pair of wheel engaging platforms with one of said platforms being adjacent one of said rail means and the other of said platforms being adjacent the other of said rail means, said means for delivering a signal comprising a plurality of load sensing devices with a pair of load sensing devices supporting one of said platforms on said frame means and another pair of load sensing devices supporting the other of said platform means on said frame means.
 10. The system of claim 9 wherein said load sensing devices are shear sensing bending beam type load cells with each of said load cells being supported at one end thereof on said frame means; the other end of each of said load cells being operatively connected to one of said platforms.
 11. The system of claim 1 wherein said vehicle engaging means comprises a loading platform with portions of said loading platform being positioned to be engaged by the wheels of the vehicle.
 12. The system of claim 11 wherein said rail means include a recess in the vehicle engaging surface with said portions of said loading platform being positioned in said recess.
 13. The system of claim 11 wherein said portions of said loading platform extend above the vehicle engaging surface of said rail means.
 14. The system of claim 4 wherein said portions of said loading platform are positioned outside of said rail means.
 15. A weighing device for weighing of railway guided vehicles comprising; frame means adapted to extend between the rails and including means for supporting said frame means solely on the rails at points spaced from the vehicle engaging surfaces of the rails, load receiving platform means comprising a pair of Longitudinally extending spaced apart beams adapted to engage and support the vehicle to be weighed, connecting means extending between said beams with said connecting means being operative to permit relative vertical movement of the ends of each beam, and a plurality of load sensing means supported on said frame means and operative to produce a signal indicative of the magnitude of an applied load, said load sensing means cooperating with said platform means to support said platform means on said frame means.
 16. The weighing device of claim 15 wherein said means for supporting said frame means comprises a pair of support rails each having a surface adapted to rest on the foot of said rails.
 17. The weighing device of claim 15 wherein said means for supporting said frame means comprises end portions on said frame means having a configuration adapted to engage and rest on the foot of the rails.
 18. The weighing device of claim 15 and further including means for selectively shifting said platform means between an operative vehicle engaging position and an inoperative position.
 19. The weighing device of claim 15 and further including roller means supported on said frame means, said roller means being adapted to engage the rails and support said device for rolling movement along the rails.
 20. The weighing device of claim 15 wherein said frame means comprises a pair of spaced apart beams and said load receiving platform means comprises a pair of wheel engaging platforms with one of said wheel engaging platforms being adjacent one of the rails and the other of said wheel engaging platforms being adjacent the other of the rails, said load sensing means comprising a plurality of signal generating devices with a pair of signal generating devices carried by one of said frame beams and another pair of signal generating devices being carried by the other of said frame beams, each of said wheel engaging platforms being supported by signal generating devices on each of said frame beams, whereby each of said frame beams is free to follow the movement of the rail on which it is supported and said wheel engaging platforms can flexibly adapt themselves relative to position and height changes of either of said frame beams. 